Thanks, ladies. It's not just the white house up for grabs. Every house of representatives is up for today and the control of the u.S. Senate is at stake. And abc's jon karl is on the other side of our election studio with that. Reporter: Good morning, elizabeth. The story as far as congress goes today, is control of the senate. Let's look where things stand. Right now, the senate has 53 democrats, 47 republicans. Today, at stake is one-third of the senate. 23 of those seats are democratic seats. Only ten republicans are up for re-elect re-election. That's why this should look like a good opportunity for republicans. There's a lot of targets of opportunity. I'm going to watch three races early in the night that pose big problems for republicans. The first, massachusetts. Scott brown, republican that won ted kennedy's seat. A very tight race now. Reporter: He is trailing badly going into against elizabeth warren. And indiana, a seat republicans have controlled for 36 years was to be safe. But richard mourdock, controversial comments on rape. And todd akin, comments about legitimate rape. YOU THINK claire McCaskill hangs on? She is leading going into election day. What does it mean if they lose those seats? Take a look. I'm going to try to show you the possibilities. If you look at it now, if they lose those seats, they're also way behind in maine. This is all early in the night. The republicans would need a net gain of seven seats to get control. That means they have to win every competitive race in the country. And I don't hear republicans even think that's possible. We'll see as it develops throughout the day. Thank you very much, jonathan karl.

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